Read ubike data
Jilung Hsieh
2018/7/3
1 Loading packages
library(httr)
library(jsonlite)
options(stringsAsFactors = FALSE)2 Getting web data
url <- "http://data.taipei/youbike"
ubike.list <- fromJSON(content(GET(url),"text", encoding = "utf-8"))
# take a glance at data
class(ubike.list) # list## [1] "list"# head(ubike.list)
# as.data.frame(ubike.list)
names(ubike.list)## [1] "retCode" "retVal"head(names(ubike.list$retVal))## [1] "0001" "0002" "0003" "0004" "0005" "0006"3 list -> vector -> matrix -> data.frame
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# Select the right node and unlist it --> vector
ubike.v <- unlist(ubike.list$retVal)
# Fold it by a specified width --> matrix
ubike.m <- matrix(ubike.v, byrow = T, ncol = 14)
# Convert the matrix to dataframe
ubike.df <- as.data.frame(ubike.m)4 Assigning variable names
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# names(ubike.df)
names(ubike.df) <- names(ubike.list$retVal$`0001`)5 Converting character vectors to numeric
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ubike.df$lng <- as.numeric(ubike.df$lng)
ubike.df$lat <- as.numeric(ubike.df$lat)
ubike.df$tot <- as.numeric(ubike.df$tot)
ubike.df$sbi <- as.numeric(ubike.df$sbi)6 Creating a new variable
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# ratio <- sbi/tot
ubike.df$ratio <- ubike.df$sbi / ubike.df$tot
summary(ubike.df)## sno sna tot sbi
## Length:401 Length:401 Min. : 22.0 Min. : 0.0
## Class :character Class :character 1st Qu.: 32.0 1st Qu.: 8.0
## Mode :character Mode :character Median : 38.0 Median :15.0
## Mean : 40.3 Mean :16.2
## 3rd Qu.: 46.0 3rd Qu.:22.0
## Max. :180.0 Max. :65.0
##
## sarea mday lat lng
## Length:401 Length:401 Min. :24.98 Min. :121.5
## Class :character Class :character 1st Qu.:25.03 1st Qu.:121.5
## Mode :character Mode :character Median :25.05 Median :121.5
## Mean :25.05 Mean :121.5
## 3rd Qu.:25.07 3rd Qu.:121.6
## Max. :25.15 Max. :121.6
## NA's :1 NA's :1
## ar sareaen snaen
## Length:401 Length:401 Length:401
## Class :character Class :character Class :character
## Mode :character Mode :character Mode :character
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## aren bemp act ratio
## Length:401 Length:401 Length:401 Min. :0.0000
## Class :character Class :character Class :character 1st Qu.:0.2273
## Mode :character Mode :character Mode :character Median :0.4062
## Mean :0.4028
## 3rd Qu.:0.5667
## Max. :1.0000
## 7 Mapping with ggmap
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library(ggplot2)
library(ggmap)
ggmap(
get_googlemap(
center=c(121.516898,25.055536),
zoom=12,
maptype='terrain')) +
geom_point(data=ubike.df,
aes(x=lng, y=lat),
colour='red',
size=ubike.df$tot/10,
alpha=0.4)## Map from URL : http://maps.googleapis.com/maps/api/staticmap?center=25.055536,121.516898&zoom=12&size=640x640&scale=2&maptype=terrain&sensor=false## Warning: Removed 1 rows containing missing values (geom_point).
8 Assigning color according to ratio levels
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NA * lapply returns a list of the same length as X, each element of which is the result of applying FUN to the corresponding element of X. * sapply is a user-friendly version and wrapper of lapply by default returning a vector
assignColor <- function(ratio){
if(ratio > 0.8){
return("#FF0000") # red
}
else if(ratio < 0.2){
return("#0000FF") # blue
}
else{
return("#00FF00") # green
}
}
ubike.df$color <- sapply(ubike.df$ratio, assignColor)9 Recoloring geom_point by ratio
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ggmap(get_googlemap(center = c(121.516898,25.055536),
zoom = 12,
maptype = 'terrain')
) +
geom_point(data = ubike.df,
aes(lng, lat),
colour = ubike.df$color,
size = ubike.df$tot/10,
alpha = 0.4)## Map from URL : http://maps.googleapis.com/maps/api/staticmap?center=25.055536,121.516898&zoom=12&size=640x640&scale=2&maptype=terrain&sensor=false## Warning: Removed 1 rows containing missing values (geom_point).